# A roller-coaster carriage travels at constant speed around a circular loop. Explain why the carriage is accelerating even though its speed does not change, and describe the direction and cause of this acceleration.

> Eduqas A-Level Physics — 1.5 Circular motion (A-Level only) · Explain · 5 marks

> A roller-coaster carriage moves at a constant speed of 12 m/s around a vertical circular loop. The carriage completes the loop without stopping.

## Mark scheme (5 marks)

1. Velocity is a vector quantity, so it has both magnitude (speed) and direction
2. The direction of motion is continuously changing as the carriage travels around the loop
3. A change in direction means a change in velocity, and a change in velocity is an acceleration
4. The acceleration is directed towards the centre of the circular loop (centripetal direction)
5. This acceleration is caused by a resultant force acting towards the centre of the loop (provided by the track pushing on the carriage / gravity / the normal contact force)

## Key terms

- [acceleration](https://www.gradenine.co.uk/glossary/acceleration)

## Related

- [Revision notes for Eduqas A-Level Physics](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

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Source: [GradeNine](https://www.gradenine.co.uk/q/a-roller-coaster-carriage-travels-at-constant-876a9d4c) · Published by Druglandscape Ltd.